Tyvek required under siding??

Old 06-29-06, 11:15 AM
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
Tyvek required under siding??

I have noticed on a lot of new construction in Middle Tennessee that tyvek is not placed under vinyl siding. Is this related to humidity? Seems like in the north all houses get tyvek. Will this practice cause problems over time? Thanks.
Old 06-29-06, 02:35 PM
Hellrazor's Avatar
Join Date: Jul 2003
Location: Eastern USA
Posts: 1,038
Received 0 Votes on 0 Posts
Yes it will cause problems. Vinyl siding has weep holes in it for a reason, thats because water can and will get behind it. They are just asking for their sheathing to rot.
Old 06-29-06, 03:39 PM
Join Date: Mar 2005
Location: USA
Posts: 6,130
Received 0 Votes on 0 Posts
Tyvek required under siding??

Vinyl siding does not even get close to being a primary waterproofing barrier. - Does that tell you something about what can happen with just Tyvek?

With the construction you describe, it will be impossible to install a window according to manufacturers instructions. - What does that do to your window guarantees?

Old 06-30-06, 10:49 AM
Pendragon's Avatar
Join Date: Jul 2002
Location: USA
Posts: 1,851
Received 2 Votes on 2 Posts
Depends on your local building code.
Where I am, a waterproof barrier wasn't required under siding until the 2004 code, which I don't think anyone started using until 2005.

Is it a good idea, absolutely! Is it required by code? Depends.
Old 06-30-06, 12:40 PM
Join Date: May 2005
Location: Central Florida
Posts: 206
Received 0 Votes on 0 Posts
ARe they using felt instead, or just nailing to the sheathing.
Old 07-02-06, 05:18 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 28,978
Received 1,447 Votes on 1,303 Posts
Building paper of some sort (tyvek, typar, felt paper) is absolutely necessary under vinyl siding. The reason it was omitted in past codes was a serious mistake, which is why it is back in the codes now.

The omission of tyvek would have NOTHING to do with humidity, because tyvek is not a vapor barrier, it is just the opposite- vapor permiable. It will allow water vapor to pass through while keeping out any liquid water penetration (when properly applied).

I'd suspect that the reason you are seeing it omitted is because those local contractors are skipping it as a way to make more money and they figure that the buyers won't know the difference once they put the siding on. It's a bad practice that should not be imitated since it runs contrary to current building standards.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: